There are believed to be communication networks from the related art in which messages are transmitted according to serial communication protocols (for example, Controller Area Network (CAN), FlexRay, Local Interconnect Network (LIN), and Media Oriented Systems Transport (MOST)). The networks include at least one data bus to which multiple user nodes are connected. It is also known for all user nodes connected to the data bus in these communication networks not to use all of the messages sent via the data bus. Each user node includes a communication module and an application. To relieve load on the host application in the user nodes, many of the communication modules forward to the application only the messages which are also used in the application. The messages are recognized on the basis of their numerical identifiers. This method is referred to as “acceptance filtering.” The known methods for acceptance filtering include lists of identifiers which are to be allowed through (so-called acceptance codes). Portions of the identifiers may be masked for the filtering, so that each list entry may stand for a group of identifiers (so-called acceptance mask). In each case n bits of the identifier may be masked with the aid of a mask, so that the identifier stands for a group of 2n identifiers. The known method may be varied using lists of identifiers which are not to be accepted, i.e., which are to be blocked. These lists are configurable using software.
When an application uses messages from a broad spectrum of identifiers, the filtering capabilities of the hardware communication module may not be adequate for passing through all necessary messages and at the same time blocking all unnecessary messages. For the remaining acceptance filtering, the application software must then expend computing power of the computing unit (central processing unit (CPU), for example) of the user node. In addition, other variables of the groups defined by the acceptance masks are possible only by overlaying, by simultaneously observing and combining multiple list entries. However, this requires time and hardware resources. A further disadvantage of the filtering using acceptance codes and acceptance masks is the risk that desired messages are inadvertently rejected. To prevent this, the acceptance mask is usually opened very wide, so that as a result messages which actually are not used at all by the application are also accepted. This results in an additional load on the application software (frequent operation of the FIFO for retrieving the message, filtering the message, etc.).
Based on the described related art, an object of the exemplary embodiments and/or exemplary methods of the present invention is to implement, with the least possible complexity, acceptance filtering having a large number of filtering criteria.